#include <cassert>
#include <unistd.h>
#include <sys/timerfd.h>

#include "TimerQueue.h"
#include "Timer.h"
#include "TimerId.h"
#include "EventLoop.h"

namespace detail {

    int createTimerfd() {
        int timerfd = ::timerfd_create(CLOCK_MONOTONIC,
                                       TFD_NONBLOCK | TFD_CLOEXEC);
        if (timerfd < 0) {}
        return timerfd;
    }

    struct timespec howMuchTimeFromNow(Timestamp when) {
        int64_t microseconds = when.microSecondsSinceEpoch()
                               - Timestamp::now().microSecondsSinceEpoch();
        if (microseconds < 100) {
            microseconds = 100;
        }
        struct timespec ts;
        ts.tv_sec = static_cast<time_t>(
                microseconds / Timestamp::kMicroSecondsPerSecond);
        ts.tv_nsec = static_cast<long>(
                (microseconds % Timestamp::kMicroSecondsPerSecond) * 1000);
        return ts;
    }

    void readTimerfd(int timerfd, Timestamp now) {
        uint64_t howmany;
        ssize_t n = ::read(timerfd, &howmany, sizeof howmany);
        // LOG_TRACE << "TimerQueue::handleRead() " << howmany << " at " << now.toString();
        if (n != sizeof howmany) {
          //  LOG_ERROR << "TimerQueue::handleRead() reads " << n << " bytes instead of 8";
        }
    }

    void resetTimerfd(int timerfd, Timestamp expiration) {
        // wake up loop by timerfd_settime()
        struct itimerspec newValue;
        struct itimerspec oldValue;
        muduo::memZero(&newValue, sizeof newValue);
        muduo::memZero(&oldValue, sizeof oldValue);
        newValue.it_value = howMuchTimeFromNow(expiration);
        int ret = ::timerfd_settime(timerfd, 0, &newValue, &oldValue);
       // if (ret) {
           //  LOG_SYSERR << "timerfd_settime()";
       // }
    }

}

TimerQueue::TimerQueue(EventLoop *loop)
        : loop_(loop),
          timerfd_(detail::createTimerfd()),
          timerfdChannel_(loop, timerfd_),
          timers_(),
          callingExpiredTimers_(false){
    timerfdChannel_.setReadCallback(
            std::bind(&TimerQueue::handleRead, this));
    // we are always reading the timerfd, we disarm it with timerfd_settime.
    timerfdChannel_.enableReading();
}

TimerQueue::~TimerQueue() {
    timerfdChannel_.disableAll();
   // timerfdChannel_.remove();
    ::close(timerfd_);
    // do not remove channel, since we're in EventLoop::dtor();
    for (const Entry &timer : timers_) {
        delete timer.second;
    }
}

TimerId TimerQueue::addTimer(const TimerCallback & cb,
                             Timestamp when,
                             double interval) {
    Timer * timer = new Timer(std::move(cb), when, interval);
    loop_->runInLoop(std::bind(&TimerQueue::addTimerInLoop, this, timer));
    return TimerId(timer, timer->sequence());
}

void TimerQueue::addTimerInLoop(Timer *timer) {
    loop_->assertInLoopThread();
    bool earliestChanged = insert(timer);
    if (earliestChanged) {
        detail::resetTimerfd(timerfd_, timer->expiration());
    }
}

/*void TimerQueue::cancel(TimerId timerId) {
    loop_->runInLoop(
            std::bind(&TimerQueue::cancelInLoop, this, timerId));
}

void TimerQueue::cancelInLoop(TimerId timerId) {
    loop_->assertInLoopThread();
    assert(timers_.size() == activeTimers_.size());
    ActiveTimer timer(timerId.timer_, timerId.sequence_);
    ActiveTimerSet::iterator it = activeTimers_.find(timer);
    if (it != activeTimers_.end()) {
        size_t n = timers_.erase(Entry(it->first->expiration(), it->first));
        assert(n == 1);
        (void) n;
        delete it->first; // FIXME: no delete please
        activeTimers_.erase(it);
    } else if (callingExpiredTimers_) {
        cancelingTimers_.insert(timer);
    }
    assert(timers_.size() == activeTimers_.size());
}*/

void TimerQueue::handleRead() {
    loop_->assertInLoopThread();
    Timestamp now(Timestamp::now());
    detail::readTimerfd(timerfd_, now);

    std::vector<Entry> expired = getExpired(now);

   // callingExpiredTimers_ = true;
   // cancelingTimers_.clear();
    // safe to callback outside critical section
    for (const Entry &it : expired) {
        it.second->run();
    }
   // callingExpiredTimers_ = false;

    reset(expired, now);
}

std::vector<TimerQueue::Entry> TimerQueue::getExpired(Timestamp now) {
    std::vector<Entry> expired;
    Entry sentry = std::make_pair(now, reinterpret_cast<Timer *>(UINTPTR_MAX));
    TimerList::iterator it = timers_.lower_bound(sentry);
    assert(it == timers_.end() || now < it->first);
    std::copy(timers_.begin(), it, std::back_inserter(expired));
    timers_.erase(timers_.begin(), it);
    return expired;
}
/*

std::vector<TimerQueue::Entry> TimerQueue::getExpired(Timestamp now) {
    assert(timers_.size() == activeTimers_.size());
    std::vector<Entry> expired;
    Entry sentry(now, reinterpret_cast<Timer *>(UINTPTR_MAX));
    TimerList::iterator end = timers_.lower_bound(sentry);
    assert(end == timers_.end() || now < end->first);
    std::copy(timers_.begin(), end, back_inserter(expired));
    timers_.erase(timers_.begin(), end);

    for (const Entry &it : expired) {
        ActiveTimer timer(it.second, it.second->sequence());
        size_t n = activeTimers_.erase(timer);
        assert(n == 1);
        (void) n;
    }

    assert(timers_.size() == activeTimers_.size());
    return expired;
}
*/

void TimerQueue::reset(const std::vector<Entry> &expired, Timestamp now) {
    /*Timestamp nextExpire;

    for (const Entry &it : expired) {
        ActiveTimer timer(it.second, it.second->sequence());
        if (it.second->repeat()
            && cancelingTimers_.find(timer) == cancelingTimers_.end()) {
            it.second->restart(now);
            insert(it.second);
        } else {
            // FIXME move to a free list
            delete it.second; // FIXME: no delete please
        }
    }

    if (!timers_.empty()) {
        nextExpire = timers_.begin()->second->expiration();
    }

    if (nextExpire.valid()) {
        resetTimerfd(timerfd_, nextExpire);
    }*/
}

bool TimerQueue::insert(Timer *timer) {
   /* loop_->assertInLoopThread();
    assert(timers_.size() == activeTimers_.size());
    bool earliestChanged = false;
    Timestamp when = timer->expiration();
    TimerList::iterator it = timers_.begin();
    if (it == timers_.end() || when < it->first) {
        earliestChanged = true;
    }
    {
        std::pair<TimerList::iterator, bool> result
                = timers_.insert(Entry(when, timer));
        assert(result.second);
        (void) result;
    }
    {
        std::pair<ActiveTimerSet::iterator, bool> result
                = activeTimers_.insert(ActiveTimer(timer, timer->sequence()));
        assert(result.second);
        (void) result;
    }

    assert(timers_.size() == activeTimers_.size());
    return earliestChanged;*/
   return true;
}
